/* CalcTools - Clean Minimal Theme */
:root {
  --blue: #2563eb;
  --blue-light: #eff6ff;
  --blue-dark: #1d4ed8;
  --blue-50: #eff6ff;
  --blue-100: #dbeafe;
  --gray-50: #fbfcfd;
  --gray-100: #f4f6f8;
  --gray-200: #eef2f6;
  --gray-300: #e2e8f0;
  --gray-400: #cbd5e1;
  --gray-500: #64748b;
  --gray-700: #334155;
  --gray-900: #0f172a;
  --radius: 14px;
  --radius-sm: 10px;
  --shadow: 0 1px 2px rgba(15,23,42,.04);
  --shadow-lg: 0 8px 24px -8px rgba(15,23,42,.08), 0 2px 6px rgba(15,23,42,.04);
  --border: 1px solid var(--gray-200);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  color: var(--gray-900);
  background: var(--gray-50);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: var(--blue); text-decoration: none; transition: color .15s; }
a:hover { color: var(--blue-dark); text-decoration: underline; }

/* Header */
.header {
  background: #fff;
  border-bottom: 1px solid var(--gray-200);
  padding: 0 1rem;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: saturate(180%) blur(8px);
}
.header-inner {
  max-width: 1080px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  gap: 1rem;
}
.logo {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--blue);
  display: flex;
  align-items: center;
  gap: .5rem;
  letter-spacing: -.01em;
}
.logo span { color: var(--gray-900); }
.nav {
  display: flex;
  align-items: center;
  gap: .15rem;
  flex-wrap: wrap;
  overflow-x: auto;
  scrollbar-width: none;
}
.nav::-webkit-scrollbar { display: none; }
.nav a {
  padding: .35rem .7rem;
  border-radius: 8px;
  font-size: .875rem;
  color: var(--gray-700);
  white-space: nowrap;
  transition: all .15s;
}
.nav a:hover, .nav a.active {
  background: var(--blue-50);
  color: var(--blue);
  text-decoration: none;
}
.lang-btn {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: 8px;
  padding: .3rem .65rem;
  cursor: pointer;
  font-size: .8rem;
  color: var(--gray-700);
  transition: all .15s;
  margin-left: .25rem;
}
.lang-btn:hover { border-color: var(--blue); color: var(--blue); background: var(--blue-50); }

/* Layout */
.container { max-width: 820px; margin: 0 auto; padding: 2.5rem 1rem 4rem; }
.container-wide { max-width: 1080px; margin: 0 auto; padding: 2.5rem 1rem 4rem; }
h1 { font-size: 1.85rem; margin-bottom: .5rem; letter-spacing: -.02em; font-weight: 700; }
.subtitle { color: var(--gray-500); margin-bottom: 2rem; font-size: 1rem; }

/* Cards */
.card {
  background: #fff;
  border: var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.75rem;
  margin-bottom: 1.5rem;
}
.card h2 { font-size: 1.15rem; margin-bottom: 1rem; }
.card h3 { font-size: 1rem; margin-bottom: .75rem; font-weight: 600; }

/* Forms */
label {
  display: block;
  font-size: .825rem;
  font-weight: 500;
  color: var(--gray-700);
  margin-bottom: .4rem;
}
input[type="number"], input[type="text"], input[type="date"], select {
  width: 100%;
  padding: .65rem .8rem;
  border: 1px solid var(--gray-300);
  border-radius: var(--radius-sm);
  font-size: .975rem;
  background: #fff;
  color: var(--gray-900);
  transition: border .15s, box-shadow .15s;
  font-family: inherit;
}
input::placeholder { color: var(--gray-400); }
input:focus, select:focus {
  outline: none;
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(37,99,235,.12);
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin-bottom: 1rem; }
.form-group { margin-bottom: 1rem; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .4rem;
  padding: .65rem 1.5rem;
  background: var(--blue);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, transform .1s;
}
.btn:hover { background: var(--blue-dark); }
.btn:active { transform: translateY(1px); }
.btn-outline { background: #fff; color: var(--blue); border: 1px solid var(--blue); }
.btn-outline:hover { background: var(--blue-50); }
.btn-sm { padding: .4rem 1rem; font-size: .85rem; }

/* Results */
.result-box { background: var(--blue-50); border-radius: var(--radius); padding: 1.5rem; margin-top: 1rem; }
.result-box .big { font-size: 2rem; font-weight: 700; color: var(--blue-dark); letter-spacing: -.02em; }
.result-box .label { font-size: .8rem; color: var(--gray-500); margin-bottom: .25rem; }
.result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 1.25rem; }

/* Table */
.table-wrap { overflow-x: auto; margin-top: 1rem; border-radius: var(--radius-sm); border: 1px solid var(--gray-200); }
table { width: 100%; border-collapse: collapse; font-size: .85rem; background: #fff; }
th, td { padding: .6rem .75rem; text-align: right; border-bottom: 1px solid var(--gray-200); }
th { background: var(--gray-50); font-weight: 600; position: sticky; top: 0; }
td:first-child, th:first-child { text-align: left; }
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: var(--blue-50); }

/* Bar chart */
.bar-chart { display: flex; align-items: flex-end; gap: 2px; height: 140px; margin-top: 1rem; }
.bar { background: var(--blue); border-radius: 3px 3px 0 0; min-width: 3px; flex: 1; transition: height .3s; }
.bar.interest { background: #f59e0b; }

/* BMI gauge */
.bmi-gauge { height: 24px; border-radius: 12px; background: linear-gradient(to right, #3b82f6 0%, #22c55e 27%, #eab308 54%, #f97316 72%, #ef4444 100%); position: relative; margin: 1.5rem 0 .5rem; }
.bmi-marker { position: absolute; top: -6px; width: 4px; height: 36px; background: var(--gray-900); border-radius: 2px; transform: translateX(-50%); transition: left .4s; }

/* Tabs */
.tabs { display: flex; gap: .25rem; margin-bottom: 1.5rem; border-bottom: 1px solid var(--gray-200); overflow-x: auto; }
.tab { padding: .6rem 1rem; cursor: pointer; font-size: .9rem; font-weight: 500; color: var(--gray-500); border-bottom: 2px solid transparent; margin-bottom: -1px; transition: all .15s; white-space: nowrap; }
.tab.active { color: var(--blue); border-bottom-color: var(--blue); }
.tab:hover { color: var(--gray-900); }

/* Radio group */
.radio-group { display: flex; gap: .5rem; margin-bottom: 1rem; flex-wrap: wrap; }
.radio-group label { display: flex; align-items: center; gap: .35rem; padding: .45rem .9rem; border: 1px solid var(--gray-300); border-radius: var(--radius-sm); cursor: pointer; font-weight: 400; font-size: .9rem; transition: all .15s; }
.radio-group label:hover { border-color: var(--blue); }
.radio-group label:has(input:checked) { border-color: var(--blue); background: var(--blue-50); color: var(--blue); }
.radio-group input { display: none; }

/* FAQ */
.faq { margin-top: 2.5rem; }
.faq h2 { font-size: 1.25rem; margin-bottom: 1rem; }
.faq details { border-bottom: 1px solid var(--gray-200); padding: .9rem 0; }
.faq summary { cursor: pointer; font-weight: 500; font-size: .95rem; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: '+'; color: var(--gray-400); font-size: 1.2rem; transition: transform .2s; }
.faq details[open] summary::after { content: '\2212'; }
.faq details p { margin-top: .6rem; font-size: .9rem; color: var(--gray-500); line-height: 1.7; }

/* Grid for index */
.calc-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 1rem; }
.calc-card {
  background: #fff;
  border: var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all .2s;
  display: block;
  color: inherit;
}
.calc-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  text-decoration: none;
}
.calc-card .icon { font-size: 1.8rem; margin-bottom: .75rem; }
.calc-card h2 { font-size: 1.05rem; margin-bottom: .35rem; font-weight: 600; }
.calc-card p { font-size: .825rem; color: var(--gray-500); line-height: 1.55; }

/* Countdown share */
.share-card { background: linear-gradient(135deg, var(--blue), #7c3aed); color: #fff; border-radius: var(--radius); padding: 2.25rem; text-align: center; margin-top: 1.5rem; }
.share-card .days { font-size: 3.5rem; font-weight: 800; letter-spacing: -.03em; }
.share-card .text { font-size: 1.05rem; opacity: .9; }

/* Footer */
.footer {
  background: #fff;
  border-top: 1px solid var(--gray-200);
  padding: 2.5rem 1rem 1.5rem;
  margin-top: 2rem;
}
.footer-inner {
  max-width: 1080px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 2rem;
  font-size: .85rem;
}
.footer-col h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .05em; color: var(--gray-500); margin-bottom: .75rem; font-weight: 600; }
.footer-col a, .footer-col p { display: block; color: var(--gray-700); margin-bottom: .4rem; font-size: .85rem; }
.footer-col a:hover { color: var(--blue); text-decoration: none; }
.footer-bottom {
  max-width: 1080px;
  margin: 1.5rem auto 0;
  padding-top: 1.25rem;
  border-top: 1px solid var(--gray-200);
  text-align: center;
  font-size: .78rem;
  color: var(--gray-500);
}
.footer-bottom a { color: inherit; }
.footer-bottom a:hover { color: var(--blue); }

/* Legal pages */
.legal { max-width: 760px; margin: 0 auto; padding: 2.5rem 1rem 4rem; }
.legal h1 { font-size: 1.75rem; margin-bottom: .5rem; }
.legal h2 { font-size: 1.15rem; margin: 1.75rem 0 .75rem; font-weight: 600; }
.legal p, .legal li { color: var(--gray-700); font-size: .92rem; line-height: 1.8; margin-bottom: .6rem; }
.legal ul, .legal ol { padding-left: 1.5rem; margin-bottom: 1rem; }
.legal .meta { color: var(--gray-500); font-size: .85rem; margin-bottom: 1.5rem; }
.legal a { color: var(--blue); }
.legal .contact-box { background: var(--blue-50); border-radius: var(--radius); padding: 1.5rem; margin: 1.5rem 0; }
.legal .contact-box p { margin-bottom: .3rem; }

/* 404 */
.not-found { max-width: 560px; margin: 0 auto; padding: 5rem 1rem; text-align: center; }
.not-found .code { font-size: 6rem; font-weight: 800; color: var(--blue); letter-spacing: -.04em; line-height: 1; }
.not-found h1 { font-size: 1.5rem; margin: 1rem 0 .5rem; }
.not-found p { color: var(--gray-500); margin-bottom: 1.5rem; }

/* Responsive */
@media (max-width: 720px) {
  .footer-inner { grid-template-columns: 1fr 1fr; gap: 1.5rem; }
}
@media (max-width: 640px) {
  .form-row { grid-template-columns: 1fr; }
  .nav { display: none; }
  h1 { font-size: 1.45rem; }
  .result-box .big { font-size: 1.5rem; }
  .header-inner { height: 52px; }
  .container, .container-wide { padding: 1.75rem 1rem 3rem; }
  .card { padding: 1.25rem; }
  .footer-inner { grid-template-columns: 1fr; gap: 1.25rem; }
  .share-card .days { font-size: 2.5rem; }
}

/* SEO content sections */
.seo-content { margin-top: 2.75rem; }
.seo-content h2 { font-size: 1.3rem; margin: 1.75rem 0 .75rem; letter-spacing: -.01em; }
.seo-content h3 { font-size: 1.05rem; margin: 1.25rem 0 .5rem; }
.seo-content > h2:first-child { margin-top: 0; }
.seo-content p { color: var(--gray-700); font-size: .92rem; margin-bottom: .8rem; line-height: 1.85; }
.seo-content ul, .seo-content ol { padding-left: 1.4rem; margin-bottom: 1rem; }
.seo-content li { color: var(--gray-700); font-size: .92rem; margin-bottom: .4rem; line-height: 1.75; }
.seo-content a { color: var(--blue); }
.seo-content .formula {
  background: var(--blue-50);
  border: 1px solid var(--blue-100);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  font-family: ui-monospace, SFMono-Regular, Consolas, 'Courier New', monospace;
  font-size: .92rem;
  line-height: 1.9;
  margin: 1rem 0 1.25rem;
  overflow-x: auto;
  color: var(--gray-900);
  white-space: pre-wrap;
}
.seo-content table { margin-bottom: 1.25rem; }
.seo-content table th, .seo-content table td { text-align: left; }
.seo-content table td:not(:first-child), .seo-content table th:not(:first-child) { text-align: left; }

/* Language toggle blocks */
[data-lang-en][hidden], [data-lang-zh][hidden] { display: none !important; }

/* Mobile nav toggle */
.nav-toggle { display: none; background: none; border: none; font-size: 1.4rem; cursor: pointer; color: var(--gray-700); padding: .25rem; }
@media (max-width: 640px) {
  .nav-toggle { display: block; }
  .nav.open {
    display: flex;
    position: absolute;
    top: 52px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: .75rem 1rem;
    border-bottom: 1px solid var(--gray-200);
    box-shadow: var(--shadow-lg);
    gap: .25rem;
  }
  .nav.open a { padding: .5rem .75rem; }
}